1. Field of the Invention
The present invention relates to an ultrasonic transducer for use in a fluid medium.
2. Description of the Related Art
Various types of ultrasonic transducers are known from the related art. By ultrasonic transducer one should generally understand, in this context, an element that is in a position to generate ultrasonic waves and/or pick up such ultrasonic waves and to convert them to electrical signals. Ultrasonic transducers are used, for instance, in fluid media for flow measurement, such as in the intake manifold or exhaust-gas tract of internal combustion engines, or in other fields of use, such as fluid-level sensors. Flow measurements may be undertaken, for example, by systems having two or more ultrasonic transducers, for instance, by evaluating running time differences. Examples of ultrasonic transducers are shown in published German patent application document DE 10 2007 010 500 A1, or in German patent applications DE 10 2008 055 123.6 and DE 10 2008 055 116.3, which are not believed to be prior art. Published Japanese patent application documents JP 2002 135894 A and JP 2002 214008 A also show corresponding ultrasonic transducers. In general, the ultrasonic transducers shown in the cited related art may also be modified according to the present invention within the scope of the present invention.
As a rule, known ultrasonic transducers have a transducer core having a piezoelement that is enclosed by a sleeve. On a radiation side, the ultrasonic transducer is in many cases closed by a sealing foil, as is described, for example in German patent applications DE 10 2008 055 116.3, in DE 10 2008 055 123.6 or in published Japanese patent application documents JP 2002 214008 A or JP 2002 135894 A.
In particular, during the manufacture of ultrasonic transducers having a sealing foil, but also in the case of other types of ultrasonic transducers, in practice, a multitude of technical challenges occurs. One technical challenge is particularly to ensure a secure and reliable fixing of the sealing foil. Especially, the mounting has to be assured in such a way that air occlusions are not able to lead to damage or reduction in quality of the ultrasonic transducer. A plurality of elements has to be particularly introduced into the inside of the housing sleeve, such as, in many cases, a damping encapsulation, wherein the insertion of the additional elements should not be able to impair the mounting quality of the foil.